libretro/tests/test_split_pack.py

"""A pack too large for one release asset is published as ZIPs, not slices.

GitHub refuses a release file of 2 GiB or more, and seven packs are larger.
They used to be cut with split(1) into `.zip.001`, `.zip.002`: byte ranges
of one archive, each under a name that still said zip and each behind its
own download link. A range opened alone is not an archive, and no tool says
that a part is missing: 7-Zip answers "Unavailable start of archive",
PowerShell "not a supported archive file format", Windows has no handler
for `.002`. Five reports in six months took a part for a broken download.

Each part is now an archive of whole files. Any tool opens it, and the
parts extracted into one folder are the pack.
"""

from __future__ import annotations

import os
import stat
import sys
import tempfile
import unittest
import zipfile
from pathlib import Path

REPO_ROOT = Path(__file__).resolve().parent.parent
sys.path.insert(0, str(REPO_ROOT / "scripts"))

import generate_pack as builder  # noqa: E402
import split_pack  # noqa: E402

LIMIT = 4096


def _payload(seed: int, size: int) -> bytes:
    """Bytes deflate cannot shrink, so a member weighs what it says."""
    return bytes((seed * 131 + n * 7919 + (n * n) % 251) % 256 for n in range(size))


class SplitFixture(unittest.TestCase):
    def setUp(self):
        self._tmp = tempfile.TemporaryDirectory()
        self.dist = Path(self._tmp.name)
        self.pack = self.dist / "Demo_1.0_BIOS_Pack.zip"
        self.members = {
            f"system/dir{n % 3}/file{n:02d}.bin": _payload(n, 900) for n in range(12)
        }
        self.members["README.txt"] = b"read me\n"
        self._build(self.pack, self.members)

    def tearDown(self):
        self._tmp.cleanup()

    @staticmethod
    def _build(path: Path, members: dict[str, bytes]) -> None:
        with zipfile.ZipFile(path, "w", zipfile.ZIP_DEFLATED) as archive:
            for name, data in members.items():
                info = zipfile.ZipInfo(name, date_time=(1980, 1, 1, 0, 0, 0))
                info.compress_type = zipfile.ZIP_DEFLATED
                info.external_attr = (0o100000 | 0o644) << 16
                archive.writestr(info, data)

    def _read(self, parts: list[Path]) -> dict[str, bytes]:
        found: dict[str, bytes] = {}
        for part in parts:
            with zipfile.ZipFile(part) as archive:
                self.assertIsNone(archive.testzip())
                for name in archive.namelist():
                    self.assertNotIn(name, found, "a file sits in two parts")
                    found[name] = archive.read(name)
        return found


class PartsAreArchives(SplitFixture):
    def test_a_pack_under_the_limit_stays_one_file(self):
        parts = split_pack.split_pack(self.pack, limit=1 << 20)
        self.assertEqual(parts, [self.pack])
        self.assertTrue(self.pack.is_file())

    def test_the_parts_extracted_together_are_the_pack(self):
        parts = split_pack.split_pack(self.pack, limit=LIMIT)
        self.assertGreater(len(parts), 1)
        self.assertEqual(self._read(parts), self.members)

    def test_every_part_fits_the_asset_limit(self):
        for part in split_pack.split_pack(self.pack, limit=LIMIT):
            self.assertLess(part.stat().st_size, LIMIT)

    def test_a_part_name_says_how_many_there_are(self):
        parts = split_pack.split_pack(self.pack, limit=LIMIT)
        count = len(parts)
        self.assertEqual(
            [part.name for part in parts],
            [
                f"Demo_1.0_BIOS_Pack.part{index}of{count}.zip"
                for index in range(1, count + 1)
            ],
        )

    def test_the_whole_archive_leaves_once_its_parts_are_checked(self):
        split_pack.split_pack(self.pack, limit=LIMIT)
        self.assertFalse(self.pack.exists())

    def test_the_same_pack_gives_the_same_parts(self):
        first = [p.read_bytes() for p in split_pack.split_pack(self.pack, limit=LIMIT)]
        other = self.dist / "again"
        other.mkdir()
        again = other / self.pack.name
        self._build(again, self.members)
        second = [p.read_bytes() for p in split_pack.split_pack(again, limit=LIMIT)]
        self.assertEqual(first, second)

    def test_a_file_no_part_can_hold_is_refused(self):
        big = self.dist / "Big_BIOS_Pack.zip"
        self._build(big, {"huge.bin": _payload(1, LIMIT * 2), "small.bin": b"x"})
        with self.assertRaises(ValueError):
            split_pack.split_pack(big, limit=LIMIT)
        self.assertTrue(big.is_file(), "the pack is kept when it cannot be split")
        self.assertEqual(sorted(p.name for p in self.dist.glob("Big*")), [big.name])

    def test_the_executable_bit_travels(self):
        tool = self.dist / "Tools_BIOS_Pack.zip"
        with zipfile.ZipFile(tool, "w", zipfile.ZIP_DEFLATED) as archive:
            info = zipfile.ZipInfo("bin/engine", date_time=(1980, 1, 1, 0, 0, 0))
            info.compress_type = zipfile.ZIP_DEFLATED
            info.external_attr = (0o100000 | 0o755) << 16
            archive.writestr(info, _payload(3, 3000))
            for n in range(4):
                archive.writestr(f"data{n}.bin", _payload(n, 900))
        parts = split_pack.split_pack(tool, limit=LIMIT)
        modes = {}
        for part in parts:
            with zipfile.ZipFile(part) as archive:
                for info in archive.infolist():
                    modes[info.filename] = info.external_attr >> 16
        self.assertTrue(modes["bin/engine"] & stat.S_IXUSR)


class PartsAreNotTakenForPacks(SplitFixture):
    def test_a_part_is_recognised_by_its_name(self):
        self.assertTrue(split_pack.is_part("RetroArch_BIOS_Pack.part1of2.zip"))
        self.assertFalse(split_pack.is_part("RetroArch_BIOS_Pack.zip"))
        self.assertFalse(split_pack.is_part("RetroArch_BIOS_Pack.zip.001"))

    def test_pack_verification_skips_the_parts(self):
        """A part holds half a platform by design: judged as a pack it fails."""
        parts = split_pack.split_pack(self.pack, limit=LIMIT)
        self.assertEqual(
            builder._pack_archives(str(self.dist)), [],
            [p.name for p in parts],
        )

    def test_the_directory_form_splits_only_what_is_too_large(self):
        small = self.dist / "Small_BIOS_Pack.zip"
        self._build(small, {"one.bin": b"1"})
        written = split_pack.split_directory(self.dist, limit=LIMIT)
        names = sorted(path.name for path in written)
        self.assertIn("Small_BIOS_Pack.zip", names)
        self.assertNotIn("Demo_1.0_BIOS_Pack.zip", names)
        self.assertTrue(all(os.path.exists(path) for path in written))


class ReleaseProcessPublishesArchives(unittest.TestCase):
    def setUp(self):
        self.text = (REPO_ROOT / "wiki" / "release-process.md").read_text(
            encoding="utf-8"
        )

    def test_it_no_longer_cuts_byte_ranges(self):
        # assertIn would print the whole page on failure.
        self.assertFalse("split --bytes" in self.text)
        self.assertTrue("scripts/split_pack.py" in self.text)

    def test_the_checksums_are_those_of_the_published_files(self):
        self.assertLess(
            self.text.index("scripts/split_pack.py"),
            self.text.index("sha256sum *.zip"),
        )


class PartsAreExplainedWhereTheyAreDownloaded(unittest.TestCase):
    PAGES = (
        "scripts/generate_readme.py",
        "scripts/generate_site.py",
        "wiki/getting-started.md",
        "wiki/troubleshooting.md",
    )

    def _text(self, relative: str) -> str:
        return (REPO_ROOT / relative).read_text(encoding="utf-8")

    def test_every_page_names_both_layouts(self):
        """The older release stays downloadable until the next one replaces it."""
        for page in self.PAGES:
            with self.subTest(page=page):
                text = self._text(page)
                self.assertTrue(".part1of2.zip" in text)
                self.assertTrue(".zip.001" in text)

    def test_the_windows_join_command_runs_from_powershell(self):
        """`copy /b A+B C` is a cmd builtin. Typed into PowerShell, the shell
        the install instructions open, it is Copy-Item and fails."""
        for page in self.PAGES:
            with self.subTest(page=page):
                for line in self._text(page).splitlines():
                    if "copy /b" in line:
                        self.assertTrue("cmd /c copy /b" in line, line.strip())


if __name__ == "__main__":
    unittest.main()